//纯函数和不纯的函数
// slice/splice
let array = [0, 1, 2, 3, 4, 5]

console.log(array.slice(0,3))
console.log(array.slice(0,3))
console.log(array.slice(0,3))

console.log(array.splice(0,3))
console.log(array.splice(0,3))
console.log(array.splice(0,3))